Lamp-screen.



H. CVPESE.

LAMP SCREEN.

APPL'lcATloN `FILED Nov, 28` 1916.

Patented J une 4, 191&

TTOR'NEY asoman.

di laf LAMP-SCREEN,

To all whom it may concern:

Be it known that I, HAROLD C. PEAsE, a citizen of the United States, residing at 1413 Union street, Schenectady, Schenectady county, State of New York, have invented certain new and useful Improvements in LampScreens; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to optical devices for controlling the transmission, projection and diffusion of light. The invention is directed primarily to the provision of a controlling means for the beam of a headlight, especially an automobile headlight, whereby a superior distribution of the light is secured andthe glare or blinding effect experienced by a person approaching the lamp is eliminated or materially reduced.

The broad object ofthe invention is to provide a novel light-controlling device for interposition in the beam from a source of light when the beam includes a plurality of parallel rays, the function of the device being to modify the'beam with particular relation to the parallel' rays so as to secure a sullicient illumination ot the distant'feld and at the same time eliminate glare and brilliantly lighted spots.

The invention involves the provisionhof a novel-type of optical screen comprisingl a plurality of translucent strands so formed and arranged as to constitute slightly separated, elongated refracting and dilracting strands or elements. This screen may consist of a single group of parallel strands or several groups with the strands of one group intersecting those of another. By means of such a screen, I have found that the beam from a source of light may be ideally controlled to satisfy various exactingconditions and requirements. Many of the parallel rays of light'emanating directly from the source of light or reflected by the parabolic reiector pass through the screen without refraction by passing through the spaces between the arallel and separated translucent strands.. hese direct rays serve to illuminate the distant eld and the degree of illumination of that field is determined by the proportion of the total amount of parallel light rays which are allowed to pass unre- Specication of Letters Patent.

iraient@a .rune a, isis..

Application'led November 28, 1916. Serial No. 133,848.

flected through the screen in this manner. This is in turn dependent upon the spacing of the strands in the screen or the ineness of .the weave of the fabric when a screen of woven fabric is employed. The remainder of the parallel rays and all or practically all of the divergent rays pass into and through the translucent strands of the screen and are refracted thereby. These rays of light are thoroughly `diused by being' deflected by the strands of the screen, thus producing a di'used light of sufficient brilliance for the illumination of the nearer ield but one which is free from spots of great brilliance and will not have a blinding eiiect rupon va person approaching the lamp.

Various materials may be employed in the translucent strands of the screen. I have found silk threadand strands of paper of circular cross-sections well adapted to this use particularly as these materials are absor ent andmay have their translucency increased by impregnating them with a suitable transparent liquid.

The translucent strands of the screen'may consist of a single series of parallel strands or several series of parallel strands with those of one series intersecting -those of the otherl or others. Preferably two series of strands are employed, one crossing the other at right angles thereto and the two series being interwoven to form a fabric. When such a screen is employed in an Iautomobile headlight with one set of strands disposed vertically and the other horizontally, two relatively narrow zones or belts of slightly increased illumination are produced, one extending vertically and the other horizontally and the two intersecting on a line eX- tending horizontally from the source of light. The position of the'headlight on` its support may be such that these paths of increased illumination aid in illuminating the field directly in front of the lampbut do not produce a blinding eli-'ect upon a person in front of the lamp but not directly in line therewith. If a single series of translucent strandsdisposed vertically be employed, there will be a single zone of increased 1llumination disposed vertically. Also, more 40 source of light including the light points 8,

number of Aroues of increased illumination Iwill be produced.

The embodiment of the invention which I prefer for use in headlights of automobiles consists of a rigid transparent sup ort 'having the screen of translucent threa s mounted thereon. The support preferably consists of two panes of glass between which the screen is mounted, the space between the two panes and around the screen bein entirely filled andi the parts being held together by a suitable transparent cement. The screen maybe a woven fabric composed merely o f a warp and a weft of parallel Silk threads. This screen is placed between two.

panesof glass and the space about the screen Ais entirelyflled with a transparent cement,

such as balsam lir; this cement not only secures the screen and the panes of glass together and excludes air from about the screen but also it impregnates the silk threads and increases 'the translucency' thereof.

The invention will 'be better understood by reference to the following description taken in connection with the accompanying p' drawing which illustrates screens embody- Isource o in the invention. n these drawings, Figure 1 is a diagrammatic view of a parabolic reector having a source of light therein and characteristic l light rays; Flg. 2 is a side elevation of a screen having a single series ofy refracting strands' Fig. 3 is a front elevation of this 9 and 10. The broken lines Llindlcate divergent unreflected rays'. The full lines 12 indicate fparallel rays emanating from the .leight direct or reflected by the parabolic r ecto'r. y The dot and dash lines 1 14.- indicate divergent rays reflected b the t of, a single series of lparallel translucent parabolic reflector, their divergence eing .due to the fact that the points of light in which they originate are not in the true focus of the reflector'.` vThe screen shown in Figs. 2 and 3 consists strands 15 of circularcrosssection mounted land held in place between'front and rear panes or lensesv 16;A These strands -15 are preferably silk threads impregnated with -fsome material .which increases their'transment 17, such as balsam ir.

lucency and they are held in place between the panes or lenses 16 by a transparent ceL In Fi s. 4: and, a screen is shown similar to that illustrated in Figs. 2 and 3. except that the screen consists of-two series of translucent strands of circular cross section instemt scribed, many of the parallel rays 12 pass through the. screen without refraction through the spaces between adjacent strands 15. The se parallel unrefracted rays 12 serve to illuminate the distant field and the proportion of theI total light thus used for the illumination of the distant. eld may be regulated as desired by choosing the requisitel spacing of the strands in the screen in proportion to the diameter of the strands. A substantial proportion of the parallel rays, including all of the parallel rays which do not pass through the spaces between adjacent strands are intercepted by the strands and re racted thereby. ln addition toy all of these parallel rays which are intercepted by the translucent strands, practically` all of the divergent rays 11and 14 are intercepted bythe' translucent strands and refracted thereby.. The total effect of this refraction of practically all of the divergent rays andthe desired proportion of the par` allel rays is to 'produce a thoroughly diffused light of sufficient illuminating power to give the desired illumination of the nearer field and, at the same time, free from spots of unusual brilliance; and the diffusion and uniformity of the light eliminates the glare andv a blmdin effect upon a person approaching the amp. v

It willrthus be seen that the screen constituting the present invention is such that a certain. proportion of the parallel rays of light, which are the rays of greatest intensty, are permitted to pass through the screen unchanged. for the purpose of llluminating the distant ield to the desired de# gree and that the remainder of the parallel rays, together with practically all of the diverentrays ofless intensity .are intercepte refracted and thoroughl diffused, resulting in Ithe production of a light which -suiciently illuminates the nearer ield and which does not blinding effect.

The filling 17 of transparent cement, preferably balsam r, is of special importance; It completely fills the spaces between the panes or lenses 16, great care beingv ob'- served in assembling the parts to prevent any air from remaining 'between the panes which would appear as bubbles and would cause undesired deflection of the light rays. Furthermore, the balsam fircement has a light density which is substantially the same as that ofglass and therefore the light` rays whlch pass throughthe spaces between ad- ]acent strands are not deflected. However, the light density of the translucent strands,

produce the objectionable v preferably ,consisting of silk threads impregnated with the cement, is diiferent from vention may have combined therewith a suitable means for reducing to an even greater extent the light passing through the upper portion of the screen so as to even more eectively guard against the blinding eEect upon a person approaching the lamp. The screen may have the translucent strands in the upper portion thereof of greater diameter and arranged closer together than those in the lower portion; or, a screen of fine mesh 'may be employed having strands omitted at regular intervals over the lower portion; or, a second screen of the .same or a different fabric or consisting of thin paper may be provided covering the upper por' tion of the main screen. Such an additional second screen may be employed when desired for further cutting down the intensity of the light emanating from the upper or tion of the lamp but the thoroughness o the diffusion of the light ei'ected by the several forms of screens herein illustrated and described is such that the use of an additionai screen for eliminating Kthe blinding eiieet upon a person approaching'V the lamp has been found to be unnecessary.

The construction herein illustrated and described also lends itself to securing various color eects. To this end a suitable coloring material may be introduced into the strands or into the cement surrounding the strands or into the glass supports for the strands or any two or more of them.- Or, diierent coloring materials may be introduced into two of these parts to obtain novel color eects.

I claim:

l. A lamp screen consisting of a translucent support and a plurality/'of strands of a fibrous material impregnated to increase their translucence, said strands being mounted on the support and spaced apart so as to permit a portion of the parallel rays from the light source to pass undelected between them while other rays are reflected by the strands; substantially as described.

2. A lamp screen consisting of a pane of glass, a plurality of translucent strands spaced apart mounted thereon, and a translucent filling in the spaces between strands; substantially as described.A

3. A lamp screen consisting of a pane of glass, two groups of translucent strands mounted thereon, the strands of each group being spaced apart and those of one group crossing those of the other, and a translucent. filling in the spaces between strands; substantially as described.

4. A lamp screen consisting of two panes of glass, a plurality of translucent strands spaced apart between them, and a translucent lling in the space between the two panes and about the strands excluding air from between the two panes; substantially as described.

5. A lamp screen consisting of a pane of glass, a plurality of translucent strands of a light density different from that of glass, the strands being mounted on the pane and spaced apart, and a filling between the strands of substantially the same light densit of that of glass; substantially as descri .A

6. A lamp screen consisting of two'panes of glass, a plurality of translucent strands of fibrous material having a light density different from that of glass, the strands being mounted between the two panes of glass and spaced apart, and a filling in the space between the two panes of glass and a out the translucent strands, said filling being of a light density which is substantially the same as that of glass; substantially as described.

In testimony whereof l afiix my signature.

HAROLD C. PEASE. 

